add(types): withExpiration field to GetInvite (#884)

Reference: https://github.com/discord/discord-api-docs/commit/2c9f17887a8e5c95d48b93901f4543beda4c09be

src/types/invites/get_invite.ts

@@ -2,4 +2,6 @@
 export interface GetInvite {
   /** Whether the invite should contain approximate member counts */
   withCounts?: boolean;
+  /** Whether the invite should contain the expiration date. */
+  withExpiration?: boolean;
 }